Ask anyone who's sceptical about CBD and you'll get the same line eventually. It's placebo. You paid £30 for a bottle of oil and your own optimism did the rest.

It's a fair challenge. Most of what we know about CBD comes from people reporting on themselves, and people are famously bad at that. We want the thing we bought to work.

Which is why a study published in Frontiers in Veterinary Science is worth your attention, even if you've never once considered CBD for dogs. Researchers looked at 47,355 dogs. Dogs don't know what CBD is. They have no expectations to live up to and no £30 to justify.

And something did shift.

What the researchers actually did

The team, led by Dr Maxwell Leung at Arizona State University, didn't run a lab trial. They tapped into something called the Dog Aging Project — a long-running community science effort where owners fill in annual surveys about their dog's diet, health, lifestyle and behaviour.

Data was collected between 2019 and 2023. Owners recorded whether their dog received CBD or hemp products daily, occasionally, or never. That gave researchers an enormous real-world picture of who's giving CBD to their dog, and what happens next.

For context: most CBD studies involve a few dozen participants. This one had tens of thousands. In a field that's been starved of decent data, that matters.

Who's actually using CBD for dogs?

Around 7.3% of dogs in the sample had been given CBD or hemp products. Of those, roughly 5.8% were frequent users, getting a dose every day.

The patterns were striking. Dogs receiving CBD were on average three years older than dogs who weren't. And certain health conditions clustered heavily:

• Dementia — 18.2% of these dogs were given CBD
• Osteoarthritis and joint problems — 12.5%
• Cancer — 10%

Male dogs were about 9% more likely to be given CBD than females. Dogs living in US states with legal medical cannabis were also more likely to receive it, which probably says more about their owners' attitudes than the dogs themselves.

Read those numbers again, though. This isn't people dosing bouncy puppies for fun. It's overwhelmingly owners of old, unwell, uncomfortable dogs looking for something — anything — that helps.

The finding everyone's talking about

Here's the part that made headlines, and it's genuinely odd.

Dogs given CBD products over several years started out more aggressive than dogs who never received them. But over time, that aggression became less intense.

"Behaviorally, dogs given CBD products for multiple years are initially more aggressive compared to dogs not receiving those products, but their aggression becomes less intense over time," said Leung.

Co-author Dr Julia Albright, of the University of Tennessee's College of Veterinary Medicine, put it plainly: this long-term behavioural change highlights CBD's potential as a therapy for canine behavioural issues.

The most likely explanation for that starting point is simple. Owners of aggressive dogs are more motivated to try CBD in the first place. They started higher because that's why they started at all.

What's strange is what didn't change. Anxiety and agitation showed no equivalent improvement. Albright flagged this herself, noting that most canine aggression stems from underlying stress or anxiety — a fight-or-flight response — so it's unclear why aggression softened while the anxious behaviours around it didn't.

Nobody has an answer yet. That's an honest gap, and it's worth saying so.

Before you get carried away

I'd be doing you a disservice if I stopped there.

This is observational research. Nobody was given a placebo, nobody was blinded, and no dog was randomly assigned to anything. It shows a pattern, not a cause.

The researchers were upfront about the limits. Owner bias is still in play — you're the one filling in the survey about the dog you love. And crucially, there was no reliable data on dosage, product type, how it was given, or where it came from. As Albright put it, we don't have a complete picture of the behavioural treatment plan.

So my earlier point about placebo needs a caveat. The dog has no expectations. The person scoring the dog's behaviour absolutely does.

There's also a safety note the team included, and it's a good one: CBD can cause side effects in dogs including stomach upset and diarrhoea, so buy from a reliable source and go carefully with dosing.

What "reliable" means in practice

If this has made you curious, the single most important thing to understand is THC.

Dogs are far more sensitive to THC than we are. Full-spectrum products contain trace amounts. For a human that's a non-issue and often a benefit. For a 9kg terrier, it isn't a risk worth taking casually.

That's why the two formats worth knowing about are broad spectrum and isolate.

Broad spectrum keeps the supporting cannabinoids but strips the THC out. Something like this 250mg broad spectrum CBD oil is a useful reference point for what that looks like — 0% THC, 8mg of CBD per ml in an MCT oil base, with minor cannabinoids like CBG and CBC retained. It's the closest commercial equivalent to what most owners in the study were likely reaching for.

Isolate goes further: 99% pure CBD, nothing else. No THC, no other cannabinoids, no hemp taste. It's the most controlled option there is, which is exactly why researchers favour it — when there's only one variable, you know what you're measuring.

One firm caveat, and please don't skip it: the products above are formulated and sold for people, not pets. Canine dosing is calculated by body weight and is nothing like a human serving. If you're considering CBD for dogs, that conversation starts with your vet, not a blog post. Ask for a certificate of analysis on anything you buy, and ask your vet about interactions if your dog is already on medication — which, given that this study was mostly about elderly dogs with chronic conditions, many are.

Why this study matters more than its headline

Strip away the dogs for a moment.

We now have behavioural data on 47,355 animals suggesting long-term CBD use tracks with a measurable change — and it's the awkward, specific, partial kind of result that fabricated findings never look like. Real data is messy. This is messy.

Leung's closing thought is the one that stuck with me: there are many similarities in how CBD may benefit dogs and humans medically.

Your dog isn't proof that CBD works. But 47,355 of them, tracked over four years, is a far more interesting starting point than another survey of people who already believed in it.

Sources:

• Conrow, K.D., et al. "Demographic features, health status, and behavioral changes associated with cannabidiol use in the Dog Aging Project." Frontiers in Veterinary Science, 2025;12. DOI: 10.3389/fvets.2025.1666663
• Frontiers, via ScienceDaily, 28 November 2025

CBD products are not medicines and cannot diagnose, treat or cure disease. Always speak to a vet before giving any supplement to an animal.